TPC, a subsidiary of THOMSON CSF, is a worldwide electronic component manufacturer, with over
40 years experience in ceramic capacitors and offers a complete package covering design, manufacture,
just-in-time delivery and quality assurance for ceramic capacitors.
Our continued development in new materials and improved technology enables us to extend the
range of products described in this brochure.
Our Sales, Marketing and Product Development Departments will provide you with full technical sup-
port to meet your requirements and help you for customized product design.
SAINT-APOLLINAIRE (France)
PENANG (Malaysia)
Information furnished is believed to be accurate and reliable. However THOMSON CSF PASSIVE
COMPONENTS assumes no responsibility for the consequences of use of such information nor for any
infringement of patents or other rights of third parties which may result from its use. No licence is
granted by implication or otherwise under any patent or patent rights of TPC. Specifications mentio-
ned in this publication are subject to change without notice. This publication supersedes and replaces
all information previously supplied. © 1997 TPC - Printed in France - All rights reserved.
These products are manufactured and commercialized by TPC.
1
Introduction
GENERAL CHARACTERISTICS
The real characteristics of a capacitor can be described
using conventional physical parameters and an equiva-
lent electrical circuit displayed hereafter :
Rp
C
Rs
Cp
Ls
R
S
or ESR (Equivalent Series Resistance) accounts
for the imperfection of the conductivity of the elec-
trodes and connections.
or series inductance depends on the geometry of
electrodes and connections, leads length ...
takes into account dielectric environment of the capa-
citor (coating ...) but is generally neglected except to
describe very high frequency behaviour of the capaci-
tor.
Rp, Rs, Ls, Cp can be considered as parasitic
effects. They generate energy losses and a depha-
sing
between voltage and current slightly different of
90°. The loss angle
δ =
(90° -
ϕ)
is commonly used
with
the tangent of loss angle which is also called :
or dissipation factor.
the quality factor is the ratio between the stored
energy and the dissipated energy. It measures the
quality of the capacitor and can be expressed as
Q = 1/tg
δ
being the frequency of the AC signal and
the pulsation of this signal with
ω
= 2
πF
the complex impedance of the capacitor is there-
fore given by the relation (neglecting Cp) :
=R+jX
1 + j Cω
Rp
(the tangent of the loss angle tg
δ
can also be
R
expressed as tg
δ
=
X
so, neglecting L
S
for L
S
ω
< 1
Cω
1
1
tg
δ
= RsCω +
+
2
Cω
RpCω
R
p
Z = Rs + j Ls
ω
+
1
L
S
Cp
C
the capacitance measures the capacitor aptitude
to store electrical charges Q under a voltage V : Q
= C.V
the rated capacitance is obtained according to the
building of the capacitor.
the dielectric constant, specific to each material
(less than 100 for type I materials, from 2000 up to
10 000 for type II materials),
the surface of the electrodes,
the thickness of the dielectric layer ; these parame-
ters determine the value of the capacitor
C = KS
t
F
ω
Z
ϕ
C
R
K
tg
δ
DF
Q
S
t
T.C.
the temperature coefficient of the capacitance is
expressed in ppm/°C for stable type I dielectrics.
is used for type II dielectrics and is expressed in %
of change of the capacitance in a fixed temperatu-
re range.
the rated voltage is the maximum voltage that can
be applied to the capacitor in continuous opera-
tion.
It can be constituted by :
a direct current component
an alternative component with
the peak voltage.
the test voltage guarantees that the capacitor
withstands U
R
with a sufficient safety margin.
represents the global losses (Polarization losses +
insulation losses).
Under DC voltage the parallel resistance is reduced to :
the insulation resistance, and measures the
imperfection of the dielectric.
F
RP
F
RS
³C/C
U
R
U
DC
U
AC
U
P
U
E
Rp
the series resonance frequency of the capacitor is
the frequency where the capacitance reactance is
exactly compensated by the inductive reactance due
to Ls
Lsω =
1
1
1
or
ω
=
or F
RS
=
Cω
LsC
2π LsC
the parallel resonance frequency occurs when Ls
is compensated by Cp :
1
F
RP
=
2π LsCp
Between F
RS
and F
RP
, the capacitor reacts as an
inductance, but still blocking DC.
Ri
4
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